Electrical plug-in connections with contact parts of the type stated above are for example used as round connectors for power transfer to motors and drives but also for signal transmission to node points in bus systems and controllers. The male and female part of a plug-in electrical connection each feature an insulating element arranged detachably in a connector housing which comprises holes arranged coaxially to the plug-in direction to accept conductive contact parts. In the female part of the electrical plug-in connection the contact parts are formed by contact bushes which, when the connection is plugged in, accept contact parts of the male part embodied as contact pins in order to establish electrical contact. The present invention relates to the production of contact parts of the female part of the plug-in connection embodied as bushing contacts or jacks.
German Application DE 100 05 297 Al discloses a known method for producing a conductive contact part for a detachable electrical connection in which a contact element in which a cage-type bushing part is provided featuring a plurality of ribs extending along parallel axes and spaced apart from one another and with a protective sleeve which can be pushed over the ribs of the bushing part with reinforced walls at its inner end. A permanent torque is now subsequently applied to the bushing part by turning it by a defined angle, preferably by 10° relative to its extended position. In a subsequent assembly step the protective sleeve is pushed onto the contact elements formed in this way and pushed forward with the reinforced end onto its contact area. The twisted ribs of the bushing part are bent inwards by the torsion process in the form of hyperbolic surfaces and in their entirety form a plurality of local contact points which are under elastic pretension around its circumference when the contact pin is plugged into the bushing part.
With this known production method it is difficult to obtain the elastic characteristics of the ribs bent inwards and thereby a defined press-on force of the ribs on an introduced contact in a reproducible way. To achieve a lasting torsion of for example 10°, in the known method the bushing part must initially be rotated by a larger angle which is to be defined, in order, because of the elastic part of the deformation after releasing the torsion to assume the plastically deformed state. This so-called over rotation of the bushing part is sensitive to material variations so that there is a certain level of scrap. In addition the ribs of the twisted bushing part form a sensitive construction which could be damaged when the protective sleeve is subsequently fitted, especially when the end of the protective sleeve with reinforced walls is to be fixed to the bushing part by pressing it on.